X ( 2 , 5 , 3 , 6 ) X ( 3 , 13 , 4 , 12 ) X ( 6 , 1 , 7 , 2 ) X ( 7 , 19 , 8 , 18 ) X ( 9 , 14 , 10 , 15 ) X ( 11 , 1 , 12 , 4 ) X ( 13 , 17 , 14 , 20 ) X ( 15 , 8 , 16 , 9 ) X ( 17 , 5 , 18 , 10 ) X ( 19 , 11 , 20 , 16 ) {\displaystyle X(2,5,3,6)X(3,13,4,12)X(6,1,7,2)X(7,19,8,18)X(9,14,10,15)X(11,1,12,4)X(13,17,14,20)X(15,8,16,9)X(17,5,18,10)X(19,11,20,16)}